+ mm-page_isolation-guard-against-possible-putback-unisolated-page.patch added to -mm tree

+ mm-page_isolation-guard-against-possible-putback-unisolated-page.patch added to -mm tree

[akpm]

The patch titled
     Subject: mm/page_isolation: guard against possible putback unisolated page
has been added to the -mm tree.  Its filename is
     mm-page_isolation-guard-against-possible-putback-unisolated-page.patch

This patch should soon appear at
    https://ozlabs.org/~akpm/mmots/broken-out/mm-page_isolation-guard-against-possible-putback-unisolated-page.patch
and later at
    https://ozlabs.org/~akpm/mmotm/broken-out/mm-page_isolation-guard-against-possible-putback-unisolated-page.patch

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------------------------------------------------------
From: Miaohe Lin <linmiaohe@huawei.com>
Subject: mm/page_isolation: guard against possible putback unisolated page

Isolating a free page in an isolated pageblock is expected to always work
as watermarks don't apply here.  But if __isolate_free_page() failed, due
to condition changes, the page will be left on the free list.  And the
page will be put back to free list again via __putback_isolated_page(). 
This may trigger VM_BUG_ON_PAGE() on page->flags checking in
__free_one_page() if PageReported is set.  Or we will corrupt the free
list because list_add() will be called for pages already on another list. 
Add a VM_WARN_ON() to complain about this change.

Link: https://lkml.kernel.org/r/20210914114508.23725-1-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/page_isolation.c |    9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

--- a/mm/page_isolation.c~mm-page_isolation-guard-against-possible-putback-unisolated-page
+++ a/mm/page_isolation.c
@@ -94,8 +94,13 @@ static void unset_migratetype_isolate(st
 			buddy = page + (buddy_pfn - pfn);
 
 			if (!is_migrate_isolate_page(buddy)) {
-				__isolate_free_page(page, order);
-				isolated_page = true;
+				isolated_page = !!__isolate_free_page(page, order);
+				/*
+				 * Isolating a free page in an isolated pageblock
+				 * is expected to always work as watermarks don't
+				 * apply here.
+				 */
+				VM_WARN_ON(!isolated_page);
 			}
 		}
 	}
_

Patches currently in -mm which might be from linmiaohe@huawei.com are

mm-page_isolation-guard-against-possible-putback-unisolated-page.patch
mm-memory_hotplug-make-hwpoisoned-dirty-swapcache-pages-unmovable.patch
mm-zsmallocc-close-race-window-between-zs_pool_dec_isolated-and-zs_unregister_migration.patch
mm-zsmallocc-combine-two-atomic-ops-in-zs_pool_dec_isolated.patch